.\" $OpenBSD: SMIME_write_CMS.3,v 1.6 2021/12/13 17:24:39 schwarze Exp $
.\" full merge up to: OpenSSL 99d63d46 Oct 26 13:56:48 2016 -0400
.\"
.\" This file was written by Dr. Stephen Henson <steve@openssl.org>.
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.Dd $Mdocdate: December 13 2021 $
.Dt SMIME_WRITE_CMS 3
.Os
.Sh NAME
.Nm SMIME_write_CMS
.Nd convert CMS structure to S/MIME format
.Sh SYNOPSIS
.In openssl/cms.h
.Ft int
.Fo SMIME_write_CMS
.Fa "BIO *out"
.Fa "CMS_ContentInfo *cms"
.Fa "BIO *data"
.Fa "int flags"
.Fc
.Sh DESCRIPTION
.Fn SMIME_write_CMS
adds the appropriate MIME headers to the
.Fa cms
structure to produce an S/MIME message and writes it to
.Fa out .
If streaming is enabled, the content must be supplied in the
.Fa data
argument.
.Pp
The following
.Fa flags
can be passed:
.Bl -tag -width Ds
.It Dv CMS_DETACHED
Use cleartext signing.
This option only makes sense if
.Fa cms
is of the type
.Vt SignedData
and
.Dv CMS_DETACHED
was also set when it was created with
.Xr CMS_sign 3 .
.Pp
If
.Dv CMS_STREAM
is not set, the data must be read twice:
once to compute the signature in
.Xr CMS_sign 3
and once to output the S/MIME message.
.It Dv CMS_TEXT
Add MIME headers for type text/plain to the content.
This only makes sense if
.Dv CMS_DETACHED
is also set.
.It Dv CMS_STREAM
Perform streaming.
This flag should only be set if
.Dv CMS_STREAM
was also passed to the function that created
.Fa cms .
.Pp
The content is output in BER format using indefinite length
constructed encoding except in the case of
.Vt SignedData
with detached content where the content is absent and DER format is
used.
.El
.Sh RETURN VALUES
.Fn SMIME_write_CMS
returns 1 for success or 0 for failure.
.Sh SEE ALSO
.Xr CMS_ContentInfo_new 3 ,
.Xr CMS_encrypt 3 ,
.Xr CMS_sign 3 ,
.Xr d2i_CMS_ContentInfo 3 ,
.Xr ERR_get_error 3 ,
.Xr SMIME_write_ASN1 3
.Sh HISTORY
.Fn SMIME_write_CMS
first appeared in OpenSSL 0.9.8h
and has been available since
.Ox 6.7 .
.Sh BUGS
.Fn SMIME_write_CMS
always base64 encodes CMS structures.
There should be an option to disable this.
